package com.leyou.item.service.impl;

import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.leyou.item.dto.CategoryDTO;
import com.leyou.item.entity.Category;
import com.leyou.item.entity.CategoryBrand;
import com.leyou.item.mapper.CategoryMapper;
import com.leyou.item.service.CategoryBrandService;
import com.leyou.item.service.CategoryService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.util.CollectionUtils;

import java.util.Collections;
import java.util.List;
import java.util.stream.Collectors;

@Service
public class CategoryServiceImpl extends ServiceImpl<CategoryMapper, Category> implements CategoryService {
    //注入 CategoryBrandService接口
    private final CategoryBrandService categoryBrandService;

    @Autowired
    public CategoryServiceImpl(CategoryBrandService categoryBrandService) {
        this.categoryBrandService = categoryBrandService;
    }

    @Override
    public List<CategoryDTO> queryCategoryByBrandId(Long brandId) {
        //1.根据品牌id , 查询中间表 ， 得到中间表对象集合
        List<CategoryBrand> CategoryBrandList = categoryBrandService.query().eq("brand_id", brandId).list();
        if (CollectionUtils.isEmpty(CategoryBrandList)){
            return Collections.emptyList(); //返回空的list
        }
        //2.获取分类id集合
        List<Long> categoryIdList = CategoryBrandList
                .stream()
                .map(CategoryBrand::getCategoryId) //遍历获取分类id，并放到categoryIdList集合
                .collect(Collectors.toList());
        //3.根据分类id集合，查询分类对象集合
        List<Category> categories = listByIds(categoryIdList);
        //4.转换DTO
        return CategoryDTO.convertEntityList(categories);

    }
}
